Process for making aniline and other arylamines



Patented Nev. 23, 1926.

UNITED "STATES PATENT OFFICE.

WILLIAM J'. HALE AND JOSEPH W. BBITTON, OF MIDLAND, MICHIGAN ASSIGNORS TO THE DOW CHEMICAL COMPANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN.

PROCESS FOR MAKING ANILINE AND OTHER .ABYLAMINES.

No Drawing.

The resent improvements relate more particu arly to a process for making arylamines by reacting between the corresponding halogenated aromatic hydrocarbon and ammonia. In 1893, Merz and Paschkowezky (J. f. prakt. Chem. (2) 48, 465) announced the production of traces of aniline through the interaction ofbromobenzine, ammonium carbonate, and dry soda lime when heated under pressure for many hours at 360-3709. In the German Patent, D. R. P. 204,951 (1907) the claim is made that an 80 er cent yield in aniline may be obtained y use of certain copper salts as catalysts upon chlorobenzene and aqueous ammonia when heated together under pressure for twenty hours at 180-200"; and still more recently, A. J, Quick (Am. Chem. Soc. 42, 1033 1920 has reported that cuprous salts are t e .e ective agents in this reaction, whereas cupric salts, when held in oxidized form, and even metallic copper itself, are without action- As a result of the foregoing reactions and of a careful study of the influence of various substances upon the possible catalysts, we have determined that cuprous salts are easily five times more effective than cupric salts and that neither copper nor any other metal, when present alone as such, has any effect as a catalyst in this reaction between chlorobenzene and aqueous ammonia.

We have, however, made the further important discovery that copper when added to a reaction mixture of halogenated benzene and aqueous ammonia containing a cuprous salt definitely promotes the catalytic effect of such salt and if suflicient copper be present to bring about a reduction of a cu-. pric salt to cuprous state, thenthe latter may be equally well used thus in combination with copper. troduction into the system of either a cuprous salt or a cupric'lisalt conjointly with the proper amount Qfficopper, a commercially successful process for the manufac-- ture of aniline'from chlorobenzene or other halogenated benzene and ammonia becomes available,

The invention then consists of the steps indicated with the detail modifications here-.

inafter fully described and particularly pointed out in the claims, the following description setting forth but several of the Accordingly, by the in-- various ways in which the principle of the invention may be'used.-

By way of comparison with the best results heretofore obtainable in a reaction of the general character in question, it may be stated th t if in a reaction mixture of chlorobenzene and aqueous ammonia containing 0.1 to 0.2 mol. of cuprous chloride, metallic copper be added, the reaction will be speeded up to such an extent that practical y complete conversion is obtained within' a few hours at 200 degrees C.;while at a slightly higher temperature, the conversion is completein less than one hour.

The following is given as a specific example of the procedure involved in carrying out our improved method or process using monochlorobenzene and aqueous ammonia with cuprous chloride and copper as cata lyst and promoter, respectively, viz:

Chlorobenzene is mixed with a 25 per cent aqueous ammonia solution in such amounts as to furnish about five mol. of

anhydrous ammonia to one mol. of the Application filed February 5, 1925; Serial No. 7,

ri'ed out in a continuous tubular heating systom to the employment of which such process is peculiarly adapted. A series ofautoclaves joined to each other may'. also be found advantageous for use in this service.

We may state further that our investiga- 'tions show that halides other than cuprous halides actually serve to retard the catalytic eflect of copper salts. This has been made evident not only by a study of the action of ammonium chloride,. sodium chloride, and similar chlorides, when added to the reaction mixture of-chlorobenzene, ammonia and cuprous chloride, but also by a study of.

the actionof halides or salts of those metals above as Well as below copper in the electromotive series of metals when added to this same reaction mixtureu Previous attempts to employ the I5 Especialy is this true w general type of reactlon herein in question involve the. entry into the solution of a molecule of ammonium] chloride simultaneously with each molecule of aniline that is formed; consequently as the conversion of halogenated benzene prof ceeds, the ammonium chloride building up necessarily retards more and more the effect of the catalyst itself, so that complete conversion was never obtainable. In our improved process on the contrary, the advantageous effect of the copper outweighs the dis advantageous effect of the ammonium chlorduring the process. en air 13 present in ride which thus builds up the system chlorobenzene-ammonia-cuprous chloride and .cop'per. In other words, the copper in the presence of ammonia combines with free oxygen with the production of cuprous oxide and thus nullifies any retardant act-ion on the part of the ammonium halide through simple interaction of the latter with the on tons oxide, more and more of suchoxide, w ich is the effective catalyst, being currentl introduced into the system. The reaction tliat occurs may be represented by the following equation When air is entirely absent from the systom, the addition of a small amount, 0.2

1 mole; of cuprous oxide gives the same result in serving to reduce the concentration of ammonium halides to a negligible factor.

In either casedonsideration oi the quantity 1 of cuprous chloride formed in process will be used to determine the quantity of the same catalyst re uired at the next stage. 1

We claim particularly to have discovered that with a maximum quantity of cuprous oxide present, in order to decompose all ammon um halides possible of formation, that 1s, 0.5. molecule of cuprous oxide per -molecule of benzene halide, there remains a particular action of copper itself, wherein the efi'ect of the catalytic action of cuprous sign that catalytic copper alone is a. promoter to cuprous salts in the ammonolysis ofhalogenatedbenzene hydrocarbonsf (By w ammonolysis We typify the same general typeof reaction known as hydrolysis, ammonia replacing water).

In conclusion, it may be stated that copper displays the same effect of a promoter to the cuprous salt catalyst in the reaction between aqueous ammonia and other polyhalogenated and substituted benzene hydrocarbons. In other words, it is to be understood that our improved process is applicable not merely to aniline or phenylamine, C H NH but to the production of the homologues of aniline or the various aryl amines in general, as illustrated by the fol- 41. Chloroanthra uinone, C H O Cl, similarly yields C NH amino-anthraquinone.

Other modes of applying the (principle of our-invention may be employe instead of the one explained, change being made as re ards the method herein disclosed, provi ed the step or steps stated by any of the following claims or the equivalentwf such m0 stated step or steps be employed.

We therefore particularly point out and distinctly claim as our invention 1. In a method of making an arylamine, the step which consists in reacting between the corresponding halogenated aromatic hy- 105 drocarbon and ammonia in the presence of a copper compound and metallic copper.

2. In a method of making an arylamine, the step which consists in reacting between the corresponding halogenated aromatic hy- 110 drocarbon and ammonia in the presence of a cuprous compound and metallic copper.

3. In a method of making an arylamine, the step which consists in reacting between the corresponding halogenated aromatic hydrocarbon and ammonia in the presence of a cuprous oxide and metallic'copper.

4. In a method of making aniline, the step which consists in reacting between a halogenatedbenzene and am onia in the presence of a copper compo nd and metallic copper. I

5. In a method of making aniline, the step which consists in reacting between mono-halogenated benzene and ammonia in the resence of a copper compound and meta, ic copper.

6. In a method of making aniline, the

step which consists in reacting between chlorobenzene and'ammonia in the presence 1 of a euprous compound and metallic copper.

7. In a method of making aniline, the step which consists in reacting between chlorobenzene and aqueous ammonia solution in approximately the proportion of one molecule of the former to five molecules of anhydrous ammonia, in the presence of a euprous compound and metallic copper.

8. In a method of making aniline, the step which consists in reacting between chlorobenzene and aqueous ammonia solution in approximately the proportion of one mole cule of the former to five moleculesof anhydrous ammonia, in the presence of from 0.1 to 0.2 molecule of a euprous compound and metallic copper.

9. In a method of making aniline, the step which consists in passing through a heated tubular system a reaction mixture of chlorobenzene and ammonia, with an addition of a euprous compound.

copper tubular systemheated rom 150 to 25Q- (3., a reaction mixture of chlorobenzene and ammonia, withan addition of a euprous compound.

12. The method of promoting the effectiveness of a copper compound as a catalyst in a reaction of the character described which consists in conducting such reaction in the presence of metallic cop er.

WILLIAM J. HALE. JOSEPH W. BRITTON.

Signed by us this 2nd day 0 February, 

